The long-term goal of the proposed research is to test the hypothesis that the maintenance of information about object identity and/or location in working memory involves the cooperative interaction of populations of neurons located in a distributed network that includes dorsolateral prefrontal, posterior parietal and inferior temporal cortical regions. To accomplish this goal, we plan to develop and implement three essential methodologies and then test the feasibility of combining them in a single experimental paradigm. First, we will train macaque monkeys to perform an oculomotor Go/No-Go delayed match-to-sample task. The task requires the animals to flexibly integrate and retain information about the identity and/or spatial location of complex visual objects, and use this information to form a rule-based behavioral decision. Second, we have designed a new type of micromanipulator that enables the semi-chronic recording of neuronal activity from up to 36 independently moveable microelectrodes housed within a single recording chamber. We plan to construct, test and optimize these devices, and then use them to record spatio-temporal patterns of neuronal activity in the dorsolateral prefrontal, posterior parietal, and inferior temporal cortical areas while the animals perform the behavioral task. Third, we have developed a comprehensive approach to the statistical quantification of neuronal correlations on a fast time scale. We plan to collect an initial body of experimental data and use these analytic methods to investigate the statistical relations of activity in these three areas at both the field potential and single unit levels. This research plan constitutes the initial phase of a long-term project to study the cortical mechanisms underlying visual cognition. For several reasons, it is particularly well suited to the goals of the R21 program. A variety of new techniques will be developed to conduct the experiments, including innovations in surgical, mechanical, electrophysiological and behavioral methods. New analytical methods will be incorporated to evaluate and interpret the resulting data. And, completion of this initial phase of the research plan will form the basis for future applications.